Abstract
Bovine tuberculosis (bTB) continues to be one of the most widely distributed chronic infectious diseases of zoonotic importance, which causes a significant economic loss in animal production. A cross-sectional study was conducted to estimate the prevalence of bTB and its associated risk factors and type the Mycobacterium bovis isolated in central Ethiopia. A total of 65 dairy farms and 654 cattle were tested for bTB using a single intradermal comparative cervical tuberculin (SICCT) test. Data on farm management, animal-related characteristics, and the owner's knowledge of the zoonotic importance of bTB were collected using a structured questionnaire. In addition, a total of 16 animals from different farms were identified for postmortem examination. Lowenstein Jensen (LJ) culture was also conducted, and spoligotyping was used to type the M. bovis strains isolated. Chi-square test and logistic regression models were used to analyze the herd- and animal-level risk factors. Herd- and animal-level prevalence rates of bTB were 58.5% (95% CI: 46.2%−69.2%) and 39.3% (95% CI: 35.5%−43.5%), respectively. At the herd level, poor farm management was the predictor for bTB positivity (p < 0.05). Animal breed, poor BCS, farm type, and poor farm management conditions were significant predictors of bTB positivity (p < 0.05) at an individual animal level. All animals identified for postmortem examination were found to have gross TB-like lesions. A total of 14 M. bovis strains were identified from 12 animals that were positive for LJ culture. The strain with the largest number of clusters (five isolates) was SB1176, followed by SB0134 (three isolates), SB0192 (two isolates), and SB2233 (two isolates), and two new strains, each consisting of only one isolate. The majority (58.5%) of the respondents did not know the zoonotic importance of bTB. The result of this study showed a high prevalence of bTB in the Addis Ababa milkshed and a low level of consciousness of the owners on its transmission to humans. Therefore, the launching of acceptable control measures of bTB and the creation of public awareness about its zoonotic transmission and prevention measures are required.
Highlights
Bovine tuberculosis is caused by Mycobacterium bovis, a member of Mycobacterium tuberculosis complex (MTBc)
In addition to their proximity to the capital Addis Ababa City, where there is a huge demand for dairy products, these localities are known for their conducive climatic conditions for dairy products
When the study sites were considered, 50.0% (19/38) of the positive herds were recorded at Sandafa followed by Sululta (23.7%), Chancho (13.2%), Laga-Tafo (10.5%), and Muka-Turi (2.6%)
Summary
Bovine tuberculosis (bTB) is caused by Mycobacterium bovis, a member of Mycobacterium tuberculosis complex (MTBc). It is a chronic infectious disease of animals characterized by the formation of granulomas primarily in the lungs, lymph nodes, intestine, and kidney. M. bovis has the widest host ranges of all MTBc organisms and can readily be transmitted to humans or a variety of domestic and wild animals [1]. In 2019 alone, the World Health Organization (WHO) reported that M. bovis was responsible for 143,000 new human TB cases and 12,300 deaths [3]. More than 91.0% of the deaths were from the African and Asian countries, where the highest prevalence of bTB has been reported [4]
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